Bus bar unit and motor

ABSTRACT

A bus bar unit may include a bus bar; and a bus bar holder comprising a resin material and configured to hold the bus bar, wherein the bus bar includes a plurality of members comprising a metal. The plurality of members may include a bent member including a radial branch, a circumferential branch, and a bent portion between the radial branch and the circumferential branch. The radial branch may include a terminal portion provided at a second end portion. The circumferential branch may include a first connection portion provided at a second end. A connection portion may be configured by connecting the first connection portion and a second connection portion provided in a second one of the plurality of members, and at least a portion of the connection portion of the bus bar is held in the bus bar holder.

CROSS REFERENCE TO RELATED APPLICATIONS

This is the U.S. national stage of application No. PCT/JP2014/075389,filed on Sep. 25, 2014. Priority under 35 U.S.C. § 119(a) and 35 U.S.C.§ 365(b) is claimed from Japanese Applications No. 2013-218195, filedOct. 21, 2013, the disclosure of which is incorporated herein byreference.

FIELD OF THE DISCLOSURE

The present disclosure relates to a bus bar unit and a motor.

BACKGROUND

The existing motor having a structure in which a conductive part calleda bus bar is disposed above a coil and the coil is electricallyconnected to an external power supply through the conductive part hasbeen known. Generally, the bus bar is formed by punching copper plateswith a press or the like. However, the existing bus bar has acomplicated shape in which it three-dimensionally extends in acircumferential direction, an axial direction, and a radial directionwith respect to a center axis of the motor. For this reason, a lot ofwasteful portions may occur in the copper plate, which is a rawmaterial, and a yield of the material may be aggravated.

In this respect, Japanese Patent Laid-Open Publication No. 2010-239771discloses an annular power feeding member in which end portions of aplurality of arc-shaped bar members are connected to each other. Theabove publication discloses that since two end portions are present forone arc-shaped bar member, there is no need to perform complicatedbending machining at the time of manufacturing the annular power feedingmember. Further, it is disclosed that the waste of material may beminimally suppressed.

In the structure disclosed in the above Japanese Patent Laid-OpenPublication No. 2010-239771, a connected portion between the arc-shapedbar members is exposed to an outside of a holding member for the powerfeeding member made of a resin material. For this reason, in thestructure of the above publication, the connected portion between thearc-shaped bar members needs to be rigid to withstand a shock upondriving of the motor or conveyance.

SUMMARY

A first exemplary embodiment of the present disclosure relates to a busbar unit used in a motor. The bus bar unit includes a bus bar and a busbar holder. The bus bar is electrically connected to a coil of themotor. The bus bar holder is made of a resin material and holds the busbar. The bus bar has a plurality of bus bar members made of a metalmaterial. The plurality of bus bar members includes a radial branchextending in a radial direction, a circumferential branch expanded in acircumferential direction, and a bent portion interposed between one endportion of the radial branch and one end portion of the circumferentialbranch. The bent bus bar member has the bent portion. The radial branchhas a terminal portion provided at the other end portion thereof. Theterminal portion is connected to a lead wire configuring the coil. Thecircumferential branch has a first connection portion provided at theother end portion thereof. A connection portion is configured byconnecting the first connection portion of the bent bus bar member to asecond connection portion installed on the other one of the plurality ofbus bar members. Further, at least a portion of the connection portionof the bus bar is held in the bus bar holder.

The above and other elements, features, steps, characteristics andadvantages of the present disclosure will become more apparent from thefollowing detailed description of the embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, withreference to the accompanying drawings which are meant to be exemplary,not limiting, and wherein like elements are numbered alike in severalFigures, in which:

FIG. 1 is a perspective view of a bus bar unit according to a firstembodiment.

FIG. 2 is a longitudinal cross-sectional view of a motor according to asecond embodiment.

FIG. 3 is a diagram conceptually illustrating a connection structure ofa coil according to a second embodiment.

FIG. 4 is a diagram conceptually illustrating a connection structure ofa coil according to a second embodiment.

FIG. 5 is a top view of a bus bar unit according to a second embodiment.

FIG. 6 is a top view of a neutral point bus bar according to a secondembodiment.

FIG. 7 is a perspective view of a neutral point bus bar according to asecond embodiment.

FIG. 8 is a perspective view of a bus bar member according to a secondembodiment.

FIG. 9 is a perspective view of a bus bar member according to a secondembodiment.

FIG. 10 is a partial perspective view of the neutral point bus bar inthe case of using arc welding.

FIG. 11 is a flow chart of a manufacturing sequence of the bus bar unitaccording to the second embodiment.

FIG. 12 is a partial exploded perspective view of a bus bar unitaccording to a modification example.

FIG. 13 is a top view of a neutral point bus bar according to anothermodification example.

FIG. 14 is a top view of a neutral point bus bar according to anothermodification example.

FIG. 15 is a top view of a neutral point bus bar according to anothermodification example.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present disclosure will bedescribed with reference to the accompanying drawings. Further, in thefollowing descriptions, a direction parallel with a center axis of amotor is called an ┌axial direction┘, a direction orthogonal to thecenter axis of the motor is called a ┌radial direction┘, and a directionalong an arc of the center axis of the motor is called a┌circumferential direction┘. Further, in the following descriptions, ashape or a positional relation of each part will be described bydefining the axial direction as a vertical direction and disposing a busbar unit above a coil. However, the definition of the vertical directionis not intended to limit a direction when manufacturing and using amotor according to the present disclosure.

The description of ┌parallel direction┘ in the present disclosure mayinclude other substantially parallel directions. Further, the┌orthogonal direction┘ in the present disclosure may include othersubstantially orthogonal directions.

1. First Embodiment

FIG. 1 is a perspective view of a bus bar unit 23A according to a firstembodiment of the present disclosure. The bus bar unit 23A is used in amotor. The bus bar unit 23A serves to electrically connect a coil 43A toan external power supply. As illustrated in FIG. 1, the bus bar unit 23Ahas a bus bar 54A and a bus bar holder 55A. The bus bar holder 55A ismade of a resin material and holds the bus bar 54A.

The bus bar 54A of FIG. 1 has two bus bar members 80A made of a metalmaterial. Each of the two bus bar members 80A has a radial branch 81Aextending in a radial direction and a circumferential branch 82Aexpanding in a circumferential direction. A bent portion 83A isinterposed between one end portion of the radial branch 81A and one endportion of the circumferential branch 82A. That is, according to thisembodiment, the two bus bar members 80A all are a bent bus bar memberwhich has the radial branch 81A, the circumferential branch 82A, and thebent portion 83A. These bent bus bar members are molded from a linearmember. For this reason, a board may be perforated without being wasted,thereby increasing a yield. Further, since these bent bus bar membershave the same shape, the yield may be more increased. In addition, sincean individual linear member is a small member, the board may beperforated without a gap, thereby increasing the yield.

The radial branch 81A has a terminal portion 84A provided at the otherend portion of an opposite side to the bent portion 83A. The terminalportion 84A is electrically connected to a lead wire 431A configuringthe coil 43A. Further, the circumferential branch 82A of the one bus barmember 80A has a first connection portion 88A provided at the other endportion of the opposite side to the bent portion 83A. The firstconnection portion 88A and the second connection portion 89A areconnected to each other to configure a connection portion 87A. Thesecond connection portion 89A is disposed on the other bus bar member80A of the two bus bar members 80A. Further, at least a portion of theconnection portion 87A is held in the bus bar holder 55A. By doing so,it is possible to increase strength of the bus bar 54A against a shock.Further, the terminal portion 84A is not covered with resin of the busbar holder 55A but is exposed.

According to this embodiment, the first connection portion 88A has afirst connection surface 85A. The second connection portion 89A has asecond connection surface 86A. As such, each connection portion has theconnection surface to be able to more firmly connect between theconnection surfaces.

2. Second Embodiment

<2-1. Overall Structure of Motor>

Next, a second embodiment of the present disclosure will be described.FIG. 2 is a longitudinal cross-sectional view of the motor 1 accordingto the second embodiment. According to this embodiment, the motor 1 isequipped in, for example, a vehicle and is used to generate a drivingforce of a power steering. However, the motor of the present disclosuremay also be used for purposes in addition to the power steering. Forexample, the motor of the present disclosure may also be used as adriving source for other portions of a vehicle, for example, a fan forengine cooling or an oil pump. As the motor of the present disclosure,any motor which is equipped in home electronics, OA equipments, medicalinstruments, etc., and generates various kinds of driving forces may beused.

The motor 1 is a so-called inner rotor type motor in which a rotor 32 isdisposed on a radially inner side of a stator 22. As illustrated in FIG.2, the motor 1 has a stationary unit 2 and a rotary unit 3. Thestationary unit 2 is fixed to an edge body of a device to be driven. Therotary unit 3 is rotatably supported by the stationary unit 2.

The stationary unit 2 has a housing 21, the stator 22, a bus bar unit23, a lower bearing portion 24, and an upper bearing portion 25.

The housing 21 has a cylindrical portion 211, a bottom plate portion212, and a cover portion 213. The cylindrical portion 211 extends in asubstantially cylindrical shape from a radially outer side of the stator22 and the bus bar unit 23 in the axial direction. The bottom plateportion 212 is expanded substantially vertically to a center axis 9 froma lower portion of the stator 22 and the rotor 32, which will bedescribed in more detail in a subsequent section. The cover portion 213is expanded substantially vertically to the center axis 9 from an upperportion of the bus bar unit 23. The stator 22, the bus bar unit 23, andthe rotor 32, which will be described in more detail in a subsequentsection, are accommodated in the housing 21.

The cylindrical portion 211, the bottom plate portion 212, and the coverportion 213 are made of metals such as aluminum and stainless. In thisembodiment, the cylindrical portion 211 and the bottom plate portion 212are configured of a single member and the cover portion 213 isconfigured of a separate member from the cylindrical portion 211 and thecover portion 213. However, the cylindrical portion 211 and the coverportion 213 may be configured of a single member and the bottom plateportion 212 may be configured of a separate member from the cylindricalportion 211 and the cover portion 213.

The stator 22 is disposed on a radially outer side of the rotor 32,which will be described in more detail in a subsequent section. Thestator 22 has a stator core 41, an insulator 42, and a plurality ofcoils 43. The stator core 41 is configured of a stacked steel sheet inwhich electromagnetic steel sheets are stacked axially. The stator core41 has an annular core back 411 and a plurality of teeth 412. The coreback 411 is disposed at substantially the same axis with the center axis9. An outer circumferential surface of the core back 411 is fixed to aninner circumferential surface of the cylindrical portion 211 of thehousing 21. The plurality of teeth 412 protrude radially inward from thecore back 411. The plurality of teeth 412 are arranged at asubstantially equal interval in the circumferential direction.

The insulator 42 is made of resin which is an insulator. Upper surfacesand lower surfaces of each tooth 412 and both end surfaces in thecircumferential direction thereof are covered with the insulator 42. Thecoil 43 is configured of a lead wire 431 wound around the insulator 42.That is, according to this embodiment, the lead wire 431 is wound aroundthe teeth 412, which is a magnetic core, through the insulator 42. Theinsulator 42 is interposed between the teeth 412 and the coil 43 toprevent the teeth 412 and the coil 43 from being electricallyshort-circuited.

Further, instead of the insulator 42, a surface of the teeth 412 maysuffer from insulating coating.

The bus bar unit 23 has bus bars 51 to 54 made of metals such as copperwhich is a conductor and a bus bar holder 55 made of a resin materialand holding the bus bars 51 to 54. The bus bars 51 to 54 areelectrically connected to the lead wire 431 configuring the coil 43.Upon the use of the motor 1, the lead wire extending from the externalpower supply is connected to the bus bars 51 to 54. That is, the coil 43and the external power supply are electrically connected to each otherthrough the bus bars 51 to 54.

In FIG. 2, the bus bar unit 23 is disposed above the stator 22 and belowthe cover portion 213. However, the bus bar unit 23 may be disposedabove the cover portion 213. A more detailed structure of the bus barunit 23 will be described below.

The lower bearing portion 24 and the upper bearing portion 25 aredisposed between the housing 21 and the shaft 31 of the rotary unit 3.According to this embodiment, as the lower bearing portion 24 and theupper bearing portion 25, a ball bearing is used. The ball bearingrotates an outer wheel and an inner wheel with respect to each otherthrough a spherical body. By doing so, the shaft 31 is rotatablysupported by the housing 21. However, instead of the ball bearing, otherbearings such as a sliding bearing and a hydraulic bearing may be usedas the lower bearing portion 24 and the upper bearing portion 25.

According to this embodiment, the rotary unit 3 has the shaft 31 and therotor 32.

The shaft 31 is a columnar member extending along the center axis 9. Theshaft 31 is preferably made of stainless steel. The shaft 31 rotatesabout the center axis 9, while being supported by the above-mentionedlower bearing portion 24 and upper bearing portion 25. An upper endportion 311 of the shaft 31 protrudes above the cover portion 213. Theupper end portion 311 is connected to an apparatus to be driven througha power delivery mechanism such as a gear.

The rotor 32 is positioned on a radially inner side of the stator 22 androtates simultaneously with the shaft 31. The rotor 32 has a rotor core61, a plurality of magnets 62, and a magnet holder 63. The rotor core 61is configured of a stacked steel sheet in which electromagnetic steelsheets are stacked axially. A center of the rotor core 61 is providedwith an insertion hole 60 extending axially. The shaft 31 ispress-fitted into the insertion hole 60. By doing so, the rotor core 61and the shaft 31 are fixed to each other.

The plurality of magnets 62 are fixed to an outer circumferentialsurface of the rotor core 61 by, for example, an adhesive. A surface ona radially outer side of each magnet 62 becomes a magnetic pole surfacefacing an end surface on a radially inner side of the teeth 412. Theplurality of magnets 62 are arranged in a circumferential direction, andN poles and S poles thereof are alternately arranged. Further, insteadof the plurality of magnets 62, one annular magnet in which the N polesand the S poles are alternately magnetized in a circumferentialdirection may be used in the rotor 32.

The magnet holder 63 is a member made of a resin material and fixed tothe rotor core 61. The magnet holder 63 is obtained by beinginsert-molded using the rotor core 61 as an insert portion. Lowersurfaces of the plurality of magnets 62 and both end surfaces in acircumferential direction thereof come in contact with the magnet holder63. By doing so, each magnet 62 is positioned in the circumferentialdirection and the axial direction. Further, the rigidity of the wholerotor 32 is increased by the magnet holder 63.

If the coil 43 is supplied with a driving current from the externalpower supply through the bus bars 51 to 54, a magnetic flux is generatedin the plurality of teeth 412 of the stator core 41. Further, a torquein the circumferential direction is generated between the rotor 32 andthe stator 22 by an action of the magnetic flux between the teeth 412and the magnet 62. As a result, the rotary unit 3 rotates about thecenter axis 9, relative to the stationary unit 2.

<2-2. Connection Configuration of Coil>

According to this embodiment, the motor 1 is a 3-phase synchronous motorwhich is driven with a 3-phase alternating current of a U phase, a Vphase, and a W phase. FIGS. 3 and 4 are diagrams conceptuallyillustrating the connection configuration of the lead wire 431configuring the coil 43. As illustrated in FIGS. 3 and 4, the stator 22has 12 coils 43. The 12 coils 43 includes four U-phase coils 43 U1 toU4, four V-phase coils 43 V1 to V4, and four W-phase coils 43 W1 to W4.These coils 43 are arranged in a circumferential direction at an equalangle interval in order of U1, V1, W1, U2, V2, W2, U3, V3, W3, U4, V4,and W4.

As conceptually illustrated in FIG. 3, six pairs of coils of U1 and U2,U3 and U4, V1 and V2, V3 and V4, W1 and W2, and W3 and W4 are eachconfigured of one continued lead wire 431. That is, as illustrated inFIG. 4, these six pairs of coils are each connected to each other inseries. The coil pair of U1 and U2 and the coil pair of U3 and U4 areconnected to each other in parallel to form a U-phase coil group UG.Further, the coil pair of V1 and V2 and the coil pair of V3 and V4 areconnected to each other in parallel to form a V-phase coil group VG.Further, the coil pair of W1 and W2 and the coil pair of W3 and W4 areconnected to each other in parallel to form a W-phase coil group WG.

One end portion of the U-phase coil group UG, one end portion of theV-phase coil group VG, and one end portion of the W-phase coil group WGare electrically connected to a circuit board 70 including amicrocontroller. Further, the other end portion of the U-phase coilgroup UG, the other end portion of the V-phase coil group VG, and theother end portion of the W-phase coil group WG are electricallyconnected to one another at a neutral point N. That is, in thisembodiment, the U-phase coil group UG, the V-phase coil group VG, andthe W-phase coil group WG are connected to one another by a Yconnection.

As Illustrated in FIGS. 3 and 4, the coils 43 U1, V1, W1, U4, V4, and W4of one side of each coil pair is disposed in a first space 71. The firstspace 71 is one space divided by a plane 73 including the center axis 9.All of the coils 43 U1, V1, W1, U4, V4, and W4 of one side of each coilpair are connected to the circuit board 70. In this embodiment, thecoils 43 U2, V2, W2, U3, V3, and W3 of the other side of each coil pairis disposed in a second space 72. The second space 72 is one spacedivided by the above-mentioned plane 73. All the coils 43 U2, V2, W2,U3, V3, and W3 of the other side of each coil pair are coils connectedto the neutral point N.

<2-3. Configuration of Bus Bar Unit>

Next, a configuration of the bus bar unit 23 used in the motor 1 bedescribed. FIG. 5 is a top view of the bus bar unit 23. As Illustratedin FIG. 5, the bus bar unit 23 has a U phase bus bar 51, a V phase busbar 52, a W phase bus bar 53, a neutral point bus bar 54, and the busbar holder 55 holding these bus bars 51 to 54. The bus bar holder 55 isa resin molding product using portions of each of the U phase bus bar51, the V phase bus bar 52, the W phase bus bar 53, and the neutralpoint bus bar 54 as an insert portion.

The U phase bus bar 51 has two U phase terminal portions 511 and 512.The two U phase terminal portions 511 and 512 are disposed in theabove-mentioned first space 71. The U phase terminal portions 511 and512 are each connected to end portions of the lead wires 431 drawn outfrom each coil 43 of U1 and U4. That is, as illustrated in FIG. 4, thecircuit board 70 and each coil 43 of U1 and U4 are electricallyconnected to each other through the U phase bus bar 51.

The V phase bus bar 52 has two V phase terminal portions 521 and 522.The two V phase terminal portions 521 and 522 are disposed in theabove-mentioned first space 71. The V phase terminal portions 521 and522 are each connected to the end portions of the lead wires 431 drawnout from each coil 43 of V1 and V4. That is, as illustrated in FIG. 4,the circuit board 70 and each coil 43 of V1 and V4 are electricallyconnected to each other through the V phase bus bar 52.

The W phase bus bar 53 has two W phase terminal portions 531 and 532.The two W phase terminal portions 531 and 532 are disposed in theabove-mentioned first space 71. The W phase terminal portions 531 and532 are each connected to the end portions of the lead wires 431 drawnout from each coil 43 of W1 and W4. That is, as illustrated in FIG. 4,the circuit board 70 and each coil 43 of W1 and W4 are electricallyconnected to each other through the W phase bus bar 53.

The neutral point bus bar 54 has six neutral point terminal portions 541to 546. The six neutral point terminal portions 541 and 546 are disposedin the above-mentioned second space 72. The six neutral point terminalportions 541 to 546 are each connected to the end portions of the leadwires 431 drawn out from each coil 43 of U2, V2, W2, U3, V3, and W3.That is, as illustrated in FIG. 4, the neutral point N and each coil ofU2, V2, W2, U3, V3, and W3 are electrically connected to each otherthrough the neutral point bus bar 54.

FIG. 6 is a top view of the neutral point bus bar 54. FIG. 7 is aperspective view of the neutral point bus bar 54. As illustrated inFIGS. 6 and 7, the neutral point bus bar 54 is configured by combining aplurality of bus bar members 80 made of a metal material. In thisembodiment, the plurality of bus bar members 80 have the same shape.These bus bar members 80 are preferably connected to each other bywelding.

FIGS. 8 and 9 are perspective views of the single bus bar member 80. Asillustrated in FIGS. 8 and 9, the bus bar member 80 is configured of aboard bent only in a thickness direction. Each of the bus bar members 80has radial branches 81 and circumferential branches 82. When beingincorporated in the motor 1, the circumferential branch 82 is expandedin the circumferential direction with respect to the center axis 9. Whenbeing incorporated in the motor 1, the radial branch 81 extends radiallyoutward from one end portion of the circumferential branch 82. Theradial branch 81 and the circumferential branch 82 are bent at a boarderdefined by a bent portion 83. That is, the bus bar member 80 has thebent portion 83 between the one end portion of the circumferentialbranch 82 and the one end portion of the radial branch 81. Further, whenbeing incorporated in the motor 1, the radial branch 81 may extendradially inward from the one end portion of the circumferential branch82.

According to this embodiment, the plurality of bus bar members 80 allare a bent bus bar member which has the radial branch 81, thecircumferential branch 82, and the bent portion 83. A waste of materialmay be reduced by configuring the neutral point bus bar 54 by combiningthe bent bus bar members obtained from the board made of a metalmaterial. However, among the plurality of bus bar members 80, a bus barmember having a different shape from the bent bus bar member may beincluded.

The radial branch 81 has a terminal portion 84 provided at the other endportion of an opposite side to the bent portion 83. Viewed from the top,the terminal portion 84 is curved in a U-letter shape. A tip of theterminal portion 84 is directed radially inward. When being incorporatedin the motor 1, the terminal portion 84 becomes one of the plurality ofneutral point terminals 541 to 546. Further, the terminal portion 84 isnot limited to a shape curved in the U-letter shape and may have anyshape which may be electrically connected to the lead wire 431.

The circumferential branch 82 has a first plate-shaped portion 821 and asecond plate-shaped portion 822. The first plate-shaped portion 821 isexpanded in a flat shape along substantially the circumferentialdirection from the other end portion of an opposite side to the bentportion 83 of the circumferential branch 82. The second plate-shapedportion 822 is expanded in the flat shape along substantially thecircumferential direction between the first plate-shaped portion 821 andthe bent portion 83. As such, when both the first plate-shaped portion821 and the second plate-shaped part 822 have a flat shape, a firstconnection surface 85 and a second connection surface 86 to be describedbelow become a plane. For this reason, compared to the case in which thefirst connection surface 85 and the second connection surface 86 are acurved surface, the contact between the first connection surface 85 andthe second connection surface 86 is stabilized. Therefore, the firstconnection surface 85 and the second connection surface 86 may be easilywelded to each other.

When the neutral point bus bar 54 is manufactured, the surface(hereinafter, referred to as the ┌first connection surface 85┘) on aradially outer side near the other end portion of the first plate-shapedportion 821 of the bus bar member 80 and the surface (hereinafter,referred to as the ┌second connection surface 86┘) on a radially innerside of the second plate-shaped portion 822 of the other bus bar member80 contact each other. In this case, a height in an axial direction ofthe first connection surface 85 coincides with a height in an axialdirection of the second connection surface 86. Further, the firstconnection surface 85 and the second connection surface 86 are welded toeach other. By doing so, the two bus bar members 80 are firmly fixed andat the same time are electrically connected to each other. The pluralityof bus bar members 80 are continued in the circumferential direction bysequentially performing the welding on the plurality of bus bar members80. As a result, as illustrated in FIGS. 6 and 7, the neutral point busbar 54 which is a single conductor is obtained.

According to this embodiment, a first connection portion 88 has thefirst connection surface 85 of the bus bar member 80. A secondconnection portion 89 has the second connection surface 86 of the otherbus bar member 80. The first connection portion 88 and the secondconnection portion 89 are connected to each other by the welding. Thefirst connection portion 88 and the second connection portion 89 arewelded to each other to configure a connection portion 87. Theconnection portion 87 is a portion thermally deformed by the welding andis a portion at which the two bus bar members 80 are connected to eachother.

The first connection surface 85 and the second connection surface 86 arepreferably connected to each other by a resistance welding. Compared tothe case of using other welding methods, the first connection surface 85and the second connection surface 86 may be easily connected to eachother by using the resistance welding. Further, as illustrated in crosshatching in FIGS. 8 and 9, the first connection surface 85 and thesecond connection surface 86 are connected to each other insubstantially circular resistance welding areas 851 and 861 by theresistance welding. Therefore, an upper edge and a lower edge of the busbar member 80 are hardly deformed by the welding.

Further, in addition to the resistance welding, the first connectionportion 88 and the second connection portion 89 may be connected to eachother by using arc welding such as TIG welding. As illustrated in FIG.10, the arc welding may be performed on the edge portions, etc., of thebus bar member 80. In FIG. 10, the edge portions of the two adjacent busbar members 80 in a TIG welding area 871 in which the welding isperformed are thermally deformed by the welding to be connected to eachother. Further, the connected portion is the connection portion 87.However, the TIG welding area 871 is not limited to the edge portion ofthe bus bar member 80 and may be portions adjacent to each other of thetwo bus bar members 80.

Here, as illustrated in FIG. 6, an angle range around the center axis 9occupied by the neutral point bus bar 54 after the welding is θo, thenumber of terminal portions included in the neutral point bus bar 54 ism, and an angle smaller than a plane angle formed by the surface of thecenter axis 9 of the first plate-shaped portion 821 and the secondconnection surface 86 is θa. Here, one interior angle of a regularpolygon in which the first plate-shaped portion 821 of the each bus barmember 80 is defined as one side is same, and therefore the angle θasatisfies the following Equation 1. In this embodiment, θo≈180°, m=6,θa≈150°, which satisfies the following Equation 1.θa≈π−θo/m  (1)

In this embodiment, the first welding surface 85 is overlappingly weldedwith the second connection surface 86 in the radial direction withrespect to the center axis 9. For this reason, the radial position ofeach of the bus bar members 80 is defined by the neighboring bus barmember 80. Therefore, a position shift hardly occurs in the radialdirection of the bus bar members 80. When the first connection surface85 overlaps with the second connection surface 86 in the circumferentialdirection, there is a need to expand the bus bar holder 55 in the radialdirection to cover the corresponding connection portion 87 whenexpanding an area of the connection portion 87. However, an area of theconnection portion 87 is limited since there is a need to expose theterminal portion 84. In contrast, when the first connection surface 85is configured to overlap with the second connection surface 86 in theradial direction, there is no need to expand the bus bar holder 55 inthe radial direction to cover the connection portion 87. Therefore,compared to the case in which the first connection surface 85 and thesecond connection surface 86 overlap with each other in thecircumferential direction, the area of the connection portion 87 may beexpanded. For this reason, the first connection portion 88 and thesecond connection portion 89 may be more firmly connected to each other.

<2-4. Manufacturing Sequence of Bus Bar Unit>

FIG. 11 is a flow chart illustrating a manufacturing sequence of the busbar unit 23. When the bus bar unit 23 is manufactured, first, theplurality of bus bar members 80 are prepared (step S1). Each of the busbar members 80 is obtained by bending the board made of a metal materialin the thickness direction by a press machine. Each of the bus barmembers 80 may be easily obtained by bending a metal plate only in thethickness direction. Further, each of the bus bar members 80 may beprecisely manufactured.

Next, the neutral point bus bar 54 is manufactured by connecting theplurality of bus bar members 80 to each other (step S2). Here, asdescribed above, the first connection surfaces 85 of each of the bus barmember 80 are welded to the second connection surfaces 86 of the bus barmembers 80 adjacent thereto. By doing so, the neutral point bus bar 54,which is the single conductor, is obtained.

Next, the U phase bus bar 51, the V phase bus bar 52, and the W phasebus bar 53 are prepared (step S3). The U phase bus bar 51, the V phasebus bar 52, and the W phase bus bar 53, for example, are obtained bybending the board made of a metal material by the press machine.Further, timing when the U phase bus bar 51, the V phase bus bar 52, andthe W phase bus bar 53 are prepared may be prior to steps S1 and S2 andmay be simultaneous with steps S1 and S2.

If the U phase bus bar 51, the V phase bus bar 52, the W phase bus bar53, and the neutral point bus bar 54 are prepared, next, these bus bars51 to 54 are disposed at the inside of a mold for resin molding (stepS4). Here, at least a portion of the respective bus bars 51 to 54 aredisposed in cavities formed by a pair of molds vertically disposed. Forthe neutral point bus bar 54, at least a portion of the connectionportion 87 is disposed in the cavity of the mold.

Next, a melted resin flows in the cavity of the mold (step S5). Themelted resin flows from a gate provided in the mold and is spread intothe cavity while contacting the U phase bus bar 51, the V phase bus bar52, the W phase bus bar 53, and a surface of the neutral point bus bar54.

When the melted resin is widely spread into the cavity of the mold, themelted resin in the mold is cooled and solidified (step S6). The meltedresin in the mold is solidified to become the bus bar holder 55.Further, the melted resin is solidified and thus the U phase bus bar 51,the V phase bus bar 52, the W phase bus bar 53, the neutral point busbar 54, and the bus bar holder 55 are fixed to one another. By doing so,the bus bar unit 23 is obtained.

Next, the pair of molds are opened and the bus bar unit 23 is releasedfrom the mold (step S7).

According to this embodiment, the bus bar unit 23 is obtained by theinsert molding. The molding of the bus bar holder 55 and the fixing ofthe bus bar holder 55 to each of the bus bars 51 to 54 may besimultaneously performed by using the insert molding. Therefore,compared to the case in which only the bus bar holder 55 is molded andthen each of the bus bars 51 to 54 are fixed to the corresponding busbar holder 55, the number of manufacture processes of the bus bar unit23 may be reduced.

At least a portion of the connection portion 87 may be completelycovered with resin configuring the bus bar holder 55 by using the insertmolding. For this reason, the fixing strength of the connection portion87 against the shock may be more increased.

3. Modification Example

Hereinabove, the exemplary embodiment of the present disclosure isdescribed but the present disclosure is not limited the above-mentionedembodiments.

FIG. 12 is a partial exploded perspective view of a bus bar unit 23Baccording to one modification example. In FIG. 12, a bus bar holder 55Bis molded separately from a neutral point bus bar 54B. The bus barholder 55B has a bus bar holding groove 551B depressed downward from anupper surface thereof. Further, after the bus bar holder 55B is molded,the neutral point bus bar 54B is inserted into the bus bar holdinggroove 551B. In this case, at least a portion of a connection portion87B of the neutral point bus bar 54B is disposed in the bus bar holdinggroove 551B. By doing so, the neutral point bus bar 54B may be held inthe bus bar holder 55B without performing the insert molding having ahigh degree of difficulty.

FIG. 13 is a top view of a neutral point bus bar 54C according toanother modification example. In FIG. 13, circumferential branches 82Cof each of the bus bar members 80C have third plate-shaped portions823C. The third plate-shaped portion 823C is expanded radially inward ina flat shape from an end portion of an opposite side to a bent portion83C of a first plate-shaped portion 821C. Further, the thirdplate-shaped portion 823C is welded to a radial branch 81C of theadjacent bus bar member 80C. That is, in FIG. 13, the third plate-shapedportion 823C has a first connection surface 85C. The radial branch 81Chas a second connection surface 86C around an end portion of the bentportion 83. For this reason, the first connection surface 85C and thesecond connection surface 86C overlap with each other in thecircumferential direction.

In FIG. 13, the angle range around the center axis occupied by theneutral point bus bar 54 after the welding is θo, the number of terminalportions included in the neutral point bus bar 54C is m, an anglesmaller than a plane angle formed by the surface of the center axis ofthe first plate-shaped portion 821C and the second connection surface86C is θa, and an angle smaller than a plane angle formed by the surfaceof the center axis of the first plate-shaped portion 821C and the firstconnection surface 85C is θb. Next, both of the angle θa and the angleθb are equal as a supplementary angle of a base angle of an isoscelestriangle formed by connecting the first plate-shaped portions 821C ofeach of the bus bar members 80C to the center axis. Therefore, theysatisfy the following Equation 2. In the example of FIG. 13, θo≈180°,m=6, θa≈θb≈105°, which satisfies the following Equation 2.θa≈θb≈(π+θo/m)/2  (2)

FIG. 14 is a top view of a neutral point bus bar 54D according toanother modification example. The neutral point bus bar 54D of FIG. 14has a plurality of first bus bar members 801D and a second bus barmember 802D. Similar to the bus bar member 80 of the above-mentionedembodiment, the first bus bar member 801D is a bent bus bar memberhaving a radial branch 81D, a circumferential branch 82D, and a bentportion 83D. However, a length in the circumferential direction of thecircumferential branch 82D is shorter than that of the circumferentialbranch 82 of the above-mentioned embodiment. The radial branch 81C has aterminal portion 84D provided at the end portion of an opposite side tothe bent portion 83C.

Meanwhile, the second bus bar member 802D has a different shape from thefirst bus bar member 801D. As illustrated in FIG. 14, the second bus barmember 802D extends in a substantially circumferential direction withrespect to the center axis of the motor.

In FIG. 14, a surface on a radially inner side of the circumferentialbranch 82D of the first bus bar member 801D is a first connectionsurface 85D. The second bus bar member 802D has a plurality of secondconnection surfaces 86D provided on a surface on a radially outer sidethereof. Further, the first connection surfaces 85D of each of thesecond bus bar members 80D are welded to the plurality of secondconnection surfaces 86D. By adopting the structure of FIG. 14, anyportion of the surface on a radially outer side of the second bus barmember 802D may be connected to the first bus bar member 801D.Therefore, even when the interval in the circumferential direction ofthe terminal portion 84D is not constant, the correspondence may beestablished.

FIG. 15 is a top view of a neutral point bus bar 54E according toanother modification example. In FIG. 15, a plurality of bus bar members80E suffers from the bending machining in a direction along a platesurface, not in the thickness direction of the plate. That is, the bentbus bar member is obtained by bending the board of a metal material in adirection along a plate surface by the press machine, etc. The bent busbar member has a bent bus bar member having a radial branch 81E, acircumferential branch 82E, and a bent portion 83E. Further, lowersurfaces of the circumferential branches 82E of each of the bus barmembers 80E are welded to upper surfaces of the adjacent bus bar members80E. Therefore, the first connection portion overlaps with the secondconnection portion in the axial direction with respect to the centeraxis of the motor. By doing so, an axial dimension of the neutral pointbus bar 54E may be more suppressed.

In FIG. 15, the bent bus bar member is obtained by bending machining theplurality of bus bar members 80E in the direction along the platesurface, not in the thickness direction of the plate. However, the boardhaving the bent shape may be perforated by the press machine, etc., toobtain the bent bus bar member.

According to the above-mentioned embodiment, the neutral point bus bar54 does not overlap with other bus bars 51 to 53 in the radialdirection. However, the neutral point bus bar may be disposed to overlapwith other bus bars in the radial direction. However, when other busbars are provided on a radially inner side of the neutral point bus baris provided with other bus bars, each terminal portion of the neutralpoint bus bar may be disposed on a radially outer side of the firstconnection portion 88. When other bus bars are provided on a radiallyouter side of the neutral point bus bar is provided with other bus bars,each terminal portion of the neutral point bus bar may be disposed on aradially inner side of the first connection portion 88. That is, eachterminal portion of the neutral point bus bar may be disposed at theopposite side to other bus bars with respect to the first connectionportion 88. By doing so, the plurality of bus bars may be effectivelyarranged as a whole.

According to the above-mentioned embodiment, the first connectionportion is welded to the second connection portion. However, the firstconnection portion may be connected to the second connection portion bymethods other than the welding. For example, the first connectionportion and the second connection portion may be connected to each otherby soldering or caulking, etc. In the case of using the soldering, aportion to which lead of the first connection portion is attached, and aportion to which lead and lead of the second connection portion areattached become the connection portion. Further, in the case of usingthe caulking, the portions contacting each other by the caulking becomesthe connection portion of the adjacent bus bar members.

The embodiment describes the example in which the present disclosure isapplied to the neutral point bus bar, but the structure of the presentdisclosure may be applied the U phase bus bar, the V phase bus bar, orthe W phase bus bar.

The present disclosure may be used in, for example, the bus bar unit andthe motor.

While embodiments of the present disclosure have been described above,it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present disclosure. The scope of the presentdisclosure, therefore, is to be determined solely by the followingclaims.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention.

The presently disclosed embodiments are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims, rather than theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

What is claimed is:
 1. A bus bar unit used in a motor comprising a coil,the bus bar, comprising: a bus bar electrically connected to the coil ofthe motor; a bus bar holder comprising a resin material and configuredto hold the bus bar, wherein the bus bar comprises a plurality of busbar members comprising a metal material, the plurality of bus barmembers comprise a bent bus bar member which comprises a radial branchextending in a radial direction, a circumferential branch expanding in acircumferential direction, and a bent portion interposed between a firstend portion of the radial branch and one a first end portion of thecircumferential branch, the radial branch comprises a terminal portionprovided at a second end portion thereof and connected to a lead wireconfiguring the coil, the circumferential branch has a first connectionportion provided at a second end portion thereof, and a connectionportion is configured by connecting the first connection portion of thebent bus bar member and a second connection portion provided in a secondone of the plurality of bus bar members, and at least a portion of theconnection portion of the bus bar is held in the bus bar holder.
 2. Thebus bar unit of claim 1, wherein the first connection portion comprisesa first connection surface, and the second connection portion comprisesa second connection surface.
 3. The bus bar unit of claim 1, wherein thebus bar holder is a resin molding product using at least a portion ofthe connection portion of the bus bar as an insert portion.
 4. The busbar unit of claim 1, wherein the bus bar holder comprises a bus barholding groove, and at least a portion of the connection portion of thebus bar is fitted in the bus bar holding groove.
 5. The bus bar unit ofclaim 1, wherein the first connection portion is welded to the secondconnection portion.
 6. The bus bar unit of claim 5, wherein the firstconnection portion is welded with the second connection portion in asubstantially circular welding area.
 7. The bus bar unit of claim 5,wherein the first connection portion and the second connection portionare welded to each other by TIG welding.
 8. The bus bar unit of claim 1,wherein the first connection portion and the second connection portionoverlap with each other in a radial direction with respect to a centeraxis.
 9. The bus bar unit of claim 1, wherein the first connectionportion and the second connection portion overlap with each other in acircumferential direction with respect to a center axis.
 10. The bus barunit of claim 1, wherein the first connection portion overlaps with thesecond connection portion in an axial direction with respect to a centeraxis.
 11. The bus bar unit of claim 1, wherein the bus bar member isconfigured of a board bent only in a thickness direction.
 12. The busbar unit of claim 2, wherein the bent bus bar member comprises thesecond connection surface on the first end portion of thecircumferential branch or the first end portion of the radial branch.13. The bus bar unit of claim 12, wherein the plurality of bus barmembers have the same shape, and each of the plurality of bus barmembers comprises the terminal portion, the first connection surface,and the second connection surface.
 14. The bus bar unit of claim 13,wherein each of the plurality of bus bar members comprises aplate-shaped portion expanded between the first connection surface andthe second connection surface.
 15. The bus bar unit of claim 14, whereinan angle range around the center axis occupied by the bus bar is θo, thenumber of terminal portions included in the bus bar is m, and an anglesmaller than a plane angle formed by a surface of the center axis of theplate-shaped portion and the second connection surface is θa to satisfythe following Equation.θa≈π−θo/m
 16. The bus bar unit of claim 14, wherein an angle rangearound the center axis occupied by the bus bar is θo, the number ofterminal portions included in the bus bar is m, an angle smaller than aplane angle formed by a surface of the center axis of the plate-shapedportion and the second connection surface is θa, and an angle smallerthan a plane angle formed by the surface of the center axis of theplate-shaped portion and the first connection surface is θb to satisfythe following Equation.θa≈θb(π+θo/m)/2
 17. The bus bar unit of claim 2, wherein the pluralityof bus bar members comprises: the terminal portion and a plurality offirst bus bar members having the first connection surface; and a secondbus bar member extending in a circumferential direction with a centeraxis of the motor, and the second bus bar member comprises a pluralityof second connection surfaces.
 18. The bus bar unit of claim 1, whereinthe bus bar unit is used in a 3-phase synchronous motor, and a neutralpoint of a Y connection and the coil are electrically connected to eachother through the bus bar.
 19. The bus bar unit of claim 1, wherein themotor comprises another bus bar overlapping with the bus bar in a radialdirection with respect to a center axis, and the terminal portion isdisposed at an opposite side to the another bus bar with respect to thefirst connection portion.
 20. The bus bar unit of claim 2, wherein aheight in a axial direction of the first connection surface is equal tothat in the axial direction of the second connection surface.
 21. Amotor, comprising: a stationary unit; and a rotary unit rotatablysupported on a center axis, wherein the stationary unit comprises: aplurality of coils arranged in a circumferential direction with respectto the center axis, and the bus bar unit described in claim 1, and therotary unit comprises: magnets facing magnetic cores of the plurality ofcoils.